#[derive(Clone, Debug)]
struct Foo {
    pub x: i32,
    pub y: i32,
}

fn foo<'a, T>() -> T {
    foo::<'a, i32>()
}

macro_rules! def_fn {
    ($($tt:tt)*) => {$($tt)*}
}

def_fn! {
    fn bar() -> u32 {
        100
    }
}

// comment
fn main() {
    println!("Hello, {}!", 92);

    let mut vec = Vec::new();
    if true {
        let x = 92;
        vec.push(Foo { x, y: 1 });
    }
    unsafe { vec.set_len(0); }

    let mut x = 42;
    let y = &mut x;
    let z = &y;

    y;
}

enum Option<T> {
    Some(T),
    None,
}
use Option::*;

impl<T> Option<T> {
    fn and<U>(self, other: Option<U>) -> Option<(T, U)> {
        match other {
            None => unimplemented!(),
            Nope => Nope,
        }
    }
}